How to Plumb a House for Hot Water

Bring hot water to your sink with CPVC pipe.

Polyvinyl chloride (PVC) pipe is widely used for residential plumbing. It's easy to install, requires few tools and has a life expectancy that exceeds most structures. However, according to the Mechanical Contracting Education and Research Foundation, PVC isn't approved for domestic hot-water systems. If you don't want to use copper for the hot-water side of your plumbing project, chlorinated polyvinyl chloride (CPVC) pipe with a maximum temperature rating of 210 degrees is an inexpensive, easy-to-install alternative.

Things You'll Need

• Measuring tape
• CPVC pipe
• CPVC fittings
• PVC tubing cutter
• CPVC solvent
• CPVC glue
• Pipe hangers

Instructions

1. Plan and measure the hot-water pipe's path. Start at the water heater: Take accurate measurements of the run to each faucet. The easiest method is usually to follow the cold-water plumbing to each outlet.

2. Make a list of necessary fittings. Again, duplicating the cold-water supply lines will usually give you a good idea of what you'll need.

3. Purchase your supplies. PVC and CPVC fittings have different inner and outer diameters and aren't interchangeable. Purchase only CPVC fittings for use on your hot-water line.

4. Follow the water heater manufacturer's instructions to connect the CPVC pipe. Many manufacturers recommend that plastic pipe not be used within 12 inches of the heater. In this case, use a 12-inch threaded steel nipple to connect the CPVC pipe to the water heater.

5. Cut and join the pipe and fittings following your planned run. Use a PVC tubing cutter to cut the pipe to length. To join the pipe to a fitting, clean the outside of the pipe and the inside of the fitting with solvent, then apply CPVC glue to the outside of the pipe. Insert the pipe into the fitting. At room temperature, the joint will be ready to handle within five minutes.

6. Install pipe hangers wherever the pipe has an unsupported run of more than 24 inches.

7. Connect all faucets to the hot-water supply.

8. Pressurize the hot-water line by turning on the supply to the water heater.

9. Check all fittings and joints for leaks.

Tips & Warnings

• CPVC pipe will expand slightly when it's heated. When plumbing between joists or frames, allow an inch or two between the end of the pipe and the building member.

• Use only CPVC glue on CPVC pipe---PVC glue will not bond sufficiently to hold up to water pressure.

• CPVC glue and cleaning solvent contain potentially toxic chemicals. If you're working in an area without adequate ventilation, use a respirator with the appropriate cartridges.

References

• PPFA.org: Installation Handbook: CPVC Hot & Cold Water Piping
• Opus.MCERF.org: Domestic Water: PVC Pipe
• GotHotWater.com: Three Common Plumbing Layouts